U.S. patent application number 17/727451 was filed with the patent office on 2022-08-04 for sensor system for vehicles, in particular motor vehicles, for detecting the vehicle speed, the vehicle level and/or the state of the vehicle suspension, arrangement for such a sensor system and vehicle having such a sensor system.
This patent application is currently assigned to Hella GmbH & Co. KGaA. The applicant listed for this patent is Hella GmbH & Co. KGaA. Invention is credited to Henning IRLE, Andreas STUMPF, Fabian Utermoehlen.
Application Number | 20220242189 17/727451 |
Document ID | / |
Family ID | 1000006344429 |
Filed Date | 2022-08-04 |
United States Patent
Application |
20220242189 |
Kind Code |
A1 |
IRLE; Henning ; et
al. |
August 4, 2022 |
SENSOR SYSTEM FOR VEHICLES, IN PARTICULAR MOTOR VEHICLES, FOR
DETECTING THE VEHICLE SPEED, THE VEHICLE LEVEL AND/OR THE STATE OF
THE VEHICLE SUSPENSION, ARRANGEMENT FOR SUCH A SENSOR SYSTEM AND
VEHICLE HAVING SUCH A SENSOR SYSTEM
Abstract
An arrangement for a sensor system for vehicles, in particular
motor vehicles, for detecting the vehicle speed, the vehicle level
and/or the state of the vehicle suspension, having a sensor for
measuring the level of a point on a vehicle body and a vibration
damper, the vibration damper comprising a first part and a second
part which are movable relative to each other, and wherein the
level sensor has an excitation coil, at least one receiver coil and
at least one electrically conductive element, wherein the
excitation coil and the at least one receiver coil are arranged on
the second part of the vibration damper and the electrically
conductive element is arranged on the first part of the vibration
damper or the first part comprises or forms the electrically
conductive element.
Inventors: |
IRLE; Henning; (Lippstadt,
DE) ; Utermoehlen; Fabian; (Lippstadt, DE) ;
STUMPF; Andreas; (Lippstadt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hella GmbH & Co. KGaA |
Lippstadt |
|
DE |
|
|
Assignee: |
Hella GmbH & Co. KGaA
Lippstadt
DE
|
Family ID: |
1000006344429 |
Appl. No.: |
17/727451 |
Filed: |
April 22, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/EP2020/077952 |
Oct 6, 2020 |
|
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17727451 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60G 2600/26 20130101;
B60G 2400/102 20130101; B60G 17/0165 20130101; B60G 2401/17
20130101; B60G 2400/41 20130101; B60G 2400/208 20130101; B60G
2400/252 20130101; B60G 2400/204 20130101; B60G 2600/042 20130101;
B60G 2800/70 20130101; B60G 17/018 20130101; B60G 17/01908
20130101; B60G 17/01933 20130101 |
International
Class: |
B60G 17/018 20060101
B60G017/018; B60G 17/019 20060101 B60G017/019; B60G 17/0165
20060101 B60G017/0165 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 22, 2019 |
DE |
10 2019 128 477.5 |
Claims
1. An arrangement for a sensor system for a vehicle for detecting a
vehicle speed, a vehicle level and/or a state of the vehicle
suspension, the arrangement comprising: a sensor to measure a level
of a point on a body of the vehicle; a vibration damper comprising
a first part and a second part that are movable relative to each
other; and a level sensor comprising an excitation coil, at least
one receiver coil, and at least one electrically conductive
element, wherein the excitation coil and the at least one receiver
coil are arranged on the second part of the vibration damper, and
wherein the electrically conductive element is arranged on the
first part of the vibration damper or the first part comprises or
forms the electrically conductive element.
2. The arrangement according to claim 1, wherein the first part of
the vibration damper is a cylinder and the second part of the
vibration damper is a tappet immersed in the first part.
3. The arrangement according to claim 2, wherein the level sensor
has a holder which is attached to the tappet and to which the
excitation coil and at least one receiver coil are attached.
4. The arrangement according to claim 3, wherein the holder is
pot-shaped and the first part is immersed in the holder.
5. The arrangement according to claim 1, wherein the level sensor
has a source for generating an excitation signal which is connected
to the excitation coil.
6. The arrangement according to claim 1, wherein the arrangement
comprises a sensor for measuring the acceleration of a point on the
vehicle perpendicular to a reference plane on the vehicle, wherein
the accelerometer is arranged on the first or second part of the
vibration damper.
7. A sensor system for vehicles, in particular motor vehicles, for
detecting a vehicle speed, a vehicle level and/or a state of the
vehicle suspension, the method comprising: at least one sensor for
measuring a point on a body of the vehicle and/or measuring, via at
least one sensor an acceleration of a point on the vehicle
perpendicular to a reference plane on the vehicle; and an
evaluation unit via which, using correlation, a time interval
between two sections of the signal curve or signal curves with high
similarity and the distance of the vehicle axles a vehicle speed
are determined from a signal curve, which is determined by the
sensor or sensors over a period of time, of a level signal provided
by the sensor and/or an acceleration signal provided by the
sensor.
8. The sensor system according to claim 7, wherein the sensor
system comprises a pair of sensors for measuring the level of a
point on a body of the vehicle.
9. The sensor system according to claim 7, wherein the sensor
system comprises a pair of sensors for measuring the acceleration
of a point on the vehicle substantially perpendicular to a
reference plane on the vehicle.
10. The sensor system according to claim 7, wherein the sensor
system comprises two pairs of the sensor for measuring the level
and at least one sensor for measuring the acceleration of an
arrangement.
11. A vehicle comprising a sensor system according to claim 7.
12. The vehicle according to claim 11 having a sensor system,
wherein a first sensor of the pair is arranged at a first point in
or on the vehicle and a second sensor of the pair is arranged at a
second point in or on the vehicle and the second point lies behind
the first point when viewed in the longitudinal direction of the
vehicle.
13. The vehicle according to claim 9, wherein, the sensor system
comprises a second pair of sensors and that a first sensor of the
second pair is located at a third point in or on the vehicle and a
second sensor of the second pair is located at a fourth point in or
on the vehicle and the fourth point lies behind the third point
when viewed in the longitudinal direction of the vehicle, and
wherein the first pair is arranged on a right-hand side of the
vehicle and the second pair is arranged on a left-hand side of the
vehicle.
14. The vehicle according to claim 11 having a sensor system,
wherein a first pair of sensors is located at a first point in or
on the vehicle and a second pair of sensors is located at a second
point in or on the vehicle and wherein the second point lies behind
the first point when viewed in the longitudinal direction of the
vehicle.
15. The vehicle according to claim 14, wherein the sensor system
comprises a third pair and a fourth pair of sensors and in that the
third pair is arranged at a third point in or on the vehicle and a
fourth pair is arranged at a fourth point in or on the vehicle and
the fourth point lies behind the third point when viewed in the
longitudinal direction of the vehicle, and wherein the first and
second pairs are arranged on a right-hand side of the vehicle and
the third and fourth pairs are arranged on a left-hand side of the
vehicle.
16. A method for detecting a vehicle speed in a vehicle according
to claim 11, the method comprising: detecting, via at least one
sensor or a sensor at a first point on the vehicle, when traveling
over ground unevenness, a change in a level of a body and/or an
acceleration of the first point on the vehicle relative to a
reference plane; and detecting a time interval, a change in the
level of the vehicle body and/or in the acceleration of a second
point on the vehicle relative to the reference plane is via the at
least one sensor or the sensor at a second point on the vehicle
when traveling over the same ground unevenness; and determining a
vehicle speed from a quotient of a known interval of the first
point and the second point and from the time interval determined
from the signals of the sensors.
17. A method for detecting a state of the vehicle suspension having
a sensor system according to claim 7, the method comprising: using
an algorithm stored in the evaluation unit for a calculation of a
course of a vibration after traveling over a ground unevenness;
calculating a target vibration curve with the vehicle suspension
intact from the load state determined from the level of the body
measured by at least one of the sensors or the sensor and from an
acceleration measured by at least one of the sensors or the sensor,
or after traveling over a ground unevenness, with the vehicle
suspension intact, a target vibration curve is read out from a
memory of the evaluation unit as a function of a load state
determined from a level of the vehicle body measured by at least
one of the sensors and from an acceleration measured by means of at
least one of the sensors; and comparing the target vibration curve,
with the vehicle suspension intact, with an actual vibration curve
measured by at least one of the sensors after traveling over a
ground unevenness.
18. A method for monitoring a tire pressure in a vehicle according
to claim 11, wherein the vehicle further comprises speed sensors
for detecting a speed of the wheels of the vehicle, the method
comprising: recording a first value for the speed of the vehicle by
the speed sensors; recording a second value for the speed of the
vehicle; comparing a first value and a second value and, in the
event of a deviation beyond a predetermined value and/or an
increase in the deviation, a signal is generated requesting the
driver to check the tire pressure.
19. A method for monitoring a steering angle of a vehicle according
to claim 11, the method comprising: detecting, when traveling over
a first ground unevenness, a change in a level of the body or in
the acceleration of a first point of the vehicle relative to a
reference plane by the sensor at the first point on the vehicle;
detecting, at a time interval, a change in a level of the body or
in the acceleration of the second point on the vehicle relative to
the reference plane at the second point on the vehicle by the
sensor, when traveling over the first ground unevenness; detecting
the time interval; determining a speed of a right side of the
vehicle from a quotient of a known interval of the first point and
the second point and from the time interval determined from the
signals of the sensors; detecting a change in the level of the body
or in the acceleration of the third point on the vehicle relative
to the reference plane by the sensor at the third point on the
vehicle when traveling over a second ground unevenness, at the same
time as traveling over the first ground unevenness, and, at a time
interval, a change in the level of the body or in the acceleration
of the fourth point on the vehicle relative to the reference plane
is detected by the sensor at the fourth point on the vehicle when
traveling over the second ground unevenness and the time interval
is detected; and determining a speed on the left-hand side of the
vehicle from the quotient of the known interval of the third point
and the fourth point and of the time interval determined from the
signals of the sensors.
Description
[0001] This nonprovisional application is a continuation of
International Application No. PCT/EP2020/077952, which was filed on
Oct. 6, 2020, and which claims priority to German Patent
Application No. 10 2019 128 477.5, which was filed in Germany on
Oct. 22, 2019, and which are both herein incorporated by
reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to a sensor system for
vehicles, in particular motor vehicles, for detecting a vehicle
speed, a vehicle level and/or a state of a vehicle suspension, an
arrangement for such a sensor system, a vehicle having such a
sensor system, a method for detecting the vehicle speed, and a
method for detecting the state of a vehicle suspension.
Description of the Background Art
[0003] A vehicle level is generally the distance of a reference
plane on a vehicle body from the ground. In practice, the level
varies as a function of the load state of the vehicle. Vehicle
level sensors known from the prior art are often based on a change
in the vertical vehicle movement due to a level change to a rotary
movement, which is then usually measured based on magnetic or
inductive principles. Such a vehicle level sensor may have a
housing that is connected to the vehicle, for example to the body,
and in which electronic components are arranged. The sensor can be
electrically connected to the rest of the vehicle via connectors. A
lever can be attached to the housing rotatable about an axis of
rotation, which has a ball at the end. This ball can be connected
to other mechanical components of the vehicle, which are attached
to the chassis, for example. Such a sensor can be used between the
chassis and the body. A linear movement between the chassis and the
body can be converted into a rotary movement by means of such a
sensor, which can then be converted into an electrical signal by
means of a rotary angle sensor.
[0004] In particular, the other mechanical components mentioned can
be complex and subject to tolerance. This can cause the accuracy of
the system including the level sensor and the mechanical components
to be inaccurate.
[0005] There is therefore a need to reduce the complexity of the
systems and increase accuracy.
[0006] Furthermore, wheel speed sensors are known, which have a
magnetic field sensor with a back bias magnet and a ferromagnetic
sensor wheel having teeth and gaps between the teeth, which rotates
about a rotary axis and is coupled to the wheel. The magnet
generates a magnetic field in which the magnetic field sensor is
arranged. At least one magnetic circuit of the magnetic field can
be detected by means of the magnetic field sensor. By moving the
teeth and gaps through the magnetic field generated by the magnet,
a change in the magnetic circuit is caused. The magnetic field
sensor scans the changes and generates a pulsed signal from the
frequency of which the wheel speed can be calculated.
[0007] The vehicle speed can be calculated back from the wheel
speed. The disadvantage here is that the speed depends on the
diameter of the wheels and is therefore also dependent on air
pressure, for example. This leads to a relatively high measurement
error, so that the speed information cannot be used, for example,
to check the plausibility of other sensors in highly automated
vehicles.
[0008] Here, too, there is a need to increase accuracy.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide an arrangement for an accurate sensor system for vehicles,
in particular motor vehicles, that is suitable for detecting a
vehicle speed and/or a vehicle level.
[0010] The object is achieved in that, according to an exemplary
embodiment of the invention, an arrangement for a sensor system is
proposed, which comprises a sensor for measuring the level of a
point on a body of the vehicle, and a vibration damper, the
vibration damper comprising a first part and a second part, which
are movable relative to each other, and the sensor having an
excitation coil, at least one receiver coil and at least one
electrically conductive element, wherein the excitation coil and
the at least one receiver coil are arranged on the first part and
the electrically conductive element on the second part of the
vibration damper, or the second part comprises or forms the
electrically conductive element.
[0011] The arrangement of sensor and vibration damper creates a
unit that allows for the level to be detected without complex
mechanics. For the sensor, the simple mechanism of the vibration
damper (also commonly referred to as shock absorber) is used, on
which the elements (excitation coil, at least one receiver coil, at
least one electrically conductive element) are arranged.
[0012] The first part of the vibration damper can be a cylinder and
the second part of the vibration damper can be a tappet immersed in
the first part. In the cylinder, a liquid, in particular an oil may
be provided that is moved in a manner known from dampers by the
tappet or a piston connected to the tappet.
[0013] The sensor may have a holder attached to the tappet. The
excitation coil and at least one receiver coil may be attached to
this holder. The holder can be pot-shaped. The first part, for
example the cylinder of the vibration damper, can be immersed in
the holder during a movement of the first part and the second part
of the vibration damper relative to one another. As a result, the
electrically conductive element provided on the second part, or the
electrically conductive element comprised or formed by the second
part and the coils arranged on the first part can be moved relative
to each other if the level of the body changes with respect to the
chassis.
[0014] The sensor may have a source for generating an excitation
signal connected to the excitation coil. The excitation signal can
have an AC voltage signal with a frequency of 1 MHz and 10 MHz
(preferably 3.5 MHz) and amplitudes in the range of a few volts.
The excitation coil can be connected in an LC oscillating
circuit.
[0015] The arrangement may have a sensor for measuring the
acceleration of a point on the vehicle perpendicular to a reference
plane on the vehicle, wherein the sensor for measuring acceleration
is arranged on the first or second part of the vibration damper.
The sensor for measuring acceleration can be an Inertial
Measurement Unit (IMU) by means of which further variables can be
measured.
[0016] The inventive idea also achieves the object of proposing a
sensor system for vehicles, in particular motor vehicles, that is
suitable for detecting the vehicle speed and/or a vehicle
level.
[0017] The object is achieved by a sensor system for vehicles, in
particular motor vehicles, for detecting the vehicle speed, the
vehicle level and/or the state of the vehicle suspension, which
comprises: at least one sensor for measuring the level of a point
on a body of the vehicle and/or at least one sensor for measuring
the acceleration of a point on the vehicle perpendicular to a
reference plane on the vehicle, an evaluation unit, by means of
which using correlation a time interval between two sections with
high similarity and the distance of the vehicle axles is determined
on the basis of a signal curve, which is determined by means of the
sensor or the sensors over a period of time, of a level signal
supplied by the sensor and/or an acceleration signal supplied by
the sensor.
[0018] If a vehicle uses a sensor system with only one sensor to
measure the level of a point on a vehicle body or only one sensor
to measure the acceleration of a point on the vehicle perpendicular
to a reference plane on the vehicle, similar measurement results
are obtained by the sensor attached to the vehicle body when
traveling over a ground unevenness, namely when traveling over the
uneven ground with the front axle and, a little later, when
traveling over the uneven ground with the rear axle. By means of
autocorrelating the measurement signal provided by the sensor,
these similarities can be determined. It is also possible to
determine the time interval between the occurrence of the
similarities. Since the distance between the vehicle axles is
known, the vehicle speed can be determined.
[0019] If a sensor system with two sensors is used in a vehicle,
these are preferably provided at the front and rear of the vehicle.
When driving over a ground unevenness, the two sensors provide
similar measurement results one after the other, namely when
traveling over the unevenness with the front axle and, a little
later, when traveling over the unevenness with the rear axle. By
cross-correlation of the measurement signals provided by the
sensors, these similarities can be determined. Furthermore, it is
possible to determine the time interval of the occurrence of the
similarities. Since the distance between the vehicle axles is
known, the speed of the vehicle can be determined.
[0020] The sensor system may have a pair of sensors to measure the
level of a point on a body of the vehicle. Alternatively, the
sensor system may have a pair of sensors to measure the
acceleration of a point on the vehicle perpendicular to a reference
plane on the vehicle. However, the sensor system can also have two
pairs of the sensor for measuring the level and the at least one
sensor for measuring acceleration.
[0021] A vehicle according to the invention may be equipped with a
sensor system according to the invention. The sensor system of a
vehicle according to the invention may have a pair of sensors. A
first sensor of the pair may be located at a first point in or on
the vehicle and a second sensor of the pair may be located at a
second point in or on the vehicle, wherein the second point lies
behind the first point when viewed in the longitudinal direction of
the vehicle. The first point can be on or near a front wheel and
the second point can be on or near a rear wheel. Preferably, the
first point and the second point are mounted on the same sides of a
vehicle. Preferably, the sensor system of a vehicle according to
the invention may have two pairs of a sensor for measuring the
level of a point on a body of the vehicle and at least one sensor
for measuring the acceleration of a point on the vehicle
perpendicular to a reference plane on the vehicle. A first pair of
sensors may be located at a first point, for example on or near a
front wheel, and a second pair at a second point, for example on or
near a rear wheel.
[0022] In a vehicle according to the invention, the vehicle speed
can be determined by means of the sensor system in that, by means
of one of the sensors or the sensor at the first point on the
vehicle, when traveling over a ground unevenness, a change in the
level of the body and/or the acceleration of the first point on the
vehicle relative to the reference plane is detected at a first
point in time and, at a time interval to a second point in time, a
change in the level of the body and/or the acceleration of the
second point on the vehicle relative to the reference plane is
detected by means of one of the sensors or the sensor at the second
point on the vehicle when traveling over the same unevenness. The
time interval can be measured. If the time interval is known, the
speed can be calculated with a known spatial distance of the first
point from the second point. For this purpose, the quotient can be
formed from the known spatial distance of the first point and the
second point and from the time interval determined from the signals
of the sensors, which corresponds to the vehicle speed. The time
interval can be determined, for example, with the aid of common
methods for similarity/pattern recognition of signals (e.g.,
cross-correlation). The course of the sensor signal of the sensor
for measuring the level and/or the sensor for measuring the
acceleration of the first pair can be compared with the
corresponding sensor signal of the second pair.
[0023] With a sensor system according to the invention, the state
of the vehicle suspension can be detected. For this purpose, after
traveling over a ground unevenness, as a function of the load state
determined on the basis of the measured level of the body and the
acceleration of the body in the direction perpendicular to a
reference plane on the vehicle, a target vibration curve is
determined, which is compared with a vibration curve measured by
means of at least one of the sensors. For example, for determining
the target vibration curve with the vehicle suspension intact, the
following two methods can be selected:
[0024] Firstly, it is possible to calculate the target vibration
curve from the measured vehicle level, which reflects the load
state, and from the measured acceleration and, if necessary, from
further known parameters determining the vibration behavior.
[0025] Secondly, it is possible to determine the target vibration
curve depending on the values measured by the sensors by looking it
up in a look-up table which is stored in a memory of the evaluation
unit.
[0026] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes, combinations, and modifications within the spirit and
scope of the invention will become apparent to those skilled in the
art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus, are
not limitive of the present invention, and wherein:
[0028] FIG. 1 is an arrangement according to the invention having a
vibration damper, a sensor for measuring the level and a sensor for
measuring acceleration,
[0029] FIG. 2 is a schematic representation of a unit comprising
the excitation coil and three receiver coils of the sensor for
measuring the level,
[0030] FIG. 3 is a schematic representation of an arrangement of
the excitation coil and a first of the receiver coils,
[0031] FIG. 4 shows a vehicle having a sensor system comprising the
sensors of two arrangements according to the invention,
[0032] FIG. 5 shows a signal curve from the sensor to measure the
level, and
[0033] FIG. 6 shows a signal curve from the sensor to measure
acceleration.
DETAILED DESCRIPTION
[0034] The example of an arrangement according to the invention
shown in FIG. 1 includes the vibration damper 300, 301, 302, 303
and a pair of 100 sensors comprising the level sensor 102 and the
accelerometer 103.
[0035] The damper 300, 301, 302, 303 essentially corresponds to a
known damper and is connected to the vehicle via two elements 301,
302. Without loss of generality, the element 301 can be assumed to
be connected to the body and the element 302 connected to the
chassis. The damper can be movable in the z-direction. A tappet 303
connected to the element 302 may be immersed into or emerge from a
cylinder 300 of the damper 300, 301, 302, 303 connected to the
element 301.
[0036] The sensor system 100 according to the invention has an
essentially pot-shaped holder 101, which is formed of electrically
non-conductive material (e.g., plastic PPE or similar). This
radially surrounds the cylinder 300 of the damper 300, 301, 302,
303 at a distance and is connected to the tappet 303 at a point
101.P1. This leads to the fact that the holder 101 also slides in
the z-direction over the cylinder 300 when the coupling element 303
is immersed in the cylinder 300 of the damper 300, 301, 302,
303.
[0037] The surface of the cylinder 300, which is covered by the
holder 101, is therefore a measure of the compression depth of the
body and thus the desired measurand for determining the vehicle
level.
[0038] The level sensor used in the example uses an inductive
measuring principle. It is a linear displacement sensor.
[0039] The linear displacement sensor 102 has a sensor circuit
board that can be integrated into the housing 101. The printed
circuit board preferably is formed of FR4 and is two- or
four-layer. It carries (see FIG. 2) at least one excitation coil
102.10, which is essentially rectangular and may have one or more
windings in one or more planes of the printed circuit board
102.
[0040] In addition, the printed circuit board 102 carries at least
one, preferably two and particularly preferably three receiver
coils 102.11, 102.12, 102.13, which may be arranged within the
excitation coil 102.10, outside the excitation coil 102.10 or both
inside and outside the excitation coil 102.10. The detailed view of
a first receiver coil 102.11 is shown in FIG. 3.
[0041] Preferably, the receiver coil 102.11 has an identical number
of right- and left-running partial turns 102.111, 102.112, which
have an essentially identical geometry and are connected in series.
FIG. 3 shows a lateral expansion (in the z-direction) of M, wherein
the transition point of the two partial turns 102.111, 102.112 is
positioned at M/2.
[0042] The other receiver coils 102.12, 102.13 are intended for a
multiphase system (FIG. 2). They can be moved relative to the
receiver coil 102.11. The displacement can be M/4 when using two
receiver coils or M/n when using n receiver coils. Optionally, the
part of the receiver coils that protrudes beyond the value M in the
negative z-direction can be supplemented in a positive z-direction
(on the opposite side of the structure).
[0043] According to the invention, the excitation coil 102.10 can
be exposed to an AC voltage which has a frequency between 1 MHz and
10 MHz (preferably 3.5 MHz) and amplitudes in the range of a few
volts. For this purpose, it may preferably be connected as a
frequency-determining element in an LC oscillating circuit.
[0044] In the receiver coils 102.11, 102.12, 102.13 voltages are
induced, which are influenced in their amplitudes by a spaced,
positioned electrically conductive element 102.20 which is attached
to the cylinder 300 of the damper. By measuring the amplitudes of
the voltages induced in the receiver coils 102.11, 102.12, 102.13,
the position of the electrically conductive element 102.20 and thus
the compression depth of the tappet 303 in the cylinder 300 can
then be calculated.
[0045] The electrically conductive element 102.20 is attached
either in or to the cylinder 300. Alternatively, however, the
cylinder 300 itself can act as a conductive element of the
inductive linear displacement sensor. For this, the cylinder 300
must have a certain electrical conductivity. With conventional
dampers, this is easily given or at least possible.
[0046] On the PCB 102 another sensor 103 is applied. This sensor
103 is an inertial measurement unit (IMU), which has at least one
accelerometer whose sensitive direction coincides with the z-axis.
Preferably, however, the IMU 103 also contains accelerometers with
other sensitive axes or rotation rate sensors.
[0047] Sensor signals of the level sensor and the IMU 103 are
preferably transmitted via the same interface. The interface can be
a PSI5 digital interface. In addition to the use of the
acceleration values for the control of adaptive chassis systems,
the information according to the invention is used to derive
further variables.
[0048] The algorithms described below can be calculated in a
vehicle control unit or in a separate sensor control unit. This
requires at least two pairs of sensors, in each case one on the
front wheel VR and one on the rear wheel HR.
[0049] To determine the vehicle speed, the following approach may
be used:
[0050] FIG. 4 shows the arrangement of two sensor pairs 100.1,
100.2 on a vehicle. FIG. 5 shows the signal of the linear
displacement sensors and FIG. 6 the signal of the IMU (only
acceleration a.sub.z in the z-direction). It is assumed that the
front wheel VR drives over a curb at time t=0, for example, and
thus experiences an acceleration that leads to an almost
exponentially subsiding linear movement z due to the spring-damper
behavior. Since the vehicle moves in the forward direction, a time
interval .DELTA.t later the rear wheel HR experiences an
approximately identical acceleration as well as a nearly identical
course of linear movement (exact course depends on the load state,
etc.). From the information .DELTA.x, which represents the distance
of the wheels of the vehicle, the vehicle speed
vx=.DELTA.x/.DELTA.t can be calculated from an evaluation unit
1000. This information can be used, for example, to check the
plausibility of other systems in the vehicle. The evaluation unit
1000 also determines the value .DELTA.t using common methods for
similarity/pattern recognition of signals (e.g.,
cross-correlation).
[0051] To determine the state of the suspension, the following
approach can be used:
[0052] In addition to the vehicle speed, the state of the
suspension can also be assessed. For this purpose, a sensor pair
100 is used. FIGS. 5 and 6 show that an acceleration (e.g., by
driving over a pothole) is followed by a certain oscillation of the
damper. This depends in its shape on the vehicle load and the state
of the suspension/damper:
[0053] The load can be estimated by determining the compression
depth of the damper. For this purpose, however, the vehicle must be
located on a flat surface. When this is the case can be detected
via the IMU.
[0054] If, for example, the suspension is broken, this affects the
post-oscillation behavior of the vehicle. This effect can be so
weak that it is not perceived by the driver. However, metrological
detection is possible.
[0055] For this purpose, an algorithm or look-up tables are stored
in the evaluation unit 1000, which calculate which post-oscillation
behavior would be expected as a function of the load state and an
acceleration. If this does not correspond to the actual measured
behavior, either the suspension or the damper is damaged, or the
air pressure of the tire has changed.
[0056] Cyclic calibration or the consideration of aging and/or
temperature influences is possible using common machine learning
methods.
[0057] By combining the vehicle level sensor 102 with an inertial
measurement unit 103, which determines at least the acceleration in
the vertical direction, an improvement in the accuracy of the level
is possible. By combining at least two sensor pairs 100.1, 100.2,
the vehicle speed can be determined.
[0058] In order to keep the tolerances of the mechanics small, a
solution is particularly preferably described in which the vehicle
level is measured directly by measuring the compression depth of
the vehicle with the aid of a linear displacement sensor 102. A
sensor system according to the invention may additionally comprise
an evaluation unit 1000, which evaluates the signals of at least
two sensor pairs 100.1, 100.2.
[0059] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are to be included within the scope of the following
claims.
* * * * *